In the rich text editor:
@Vallendoria
In a comment:
[Vallendoria](https://www.worldofgaia.org/user/Vallendoria)
For Names and Avatars:
In the rich text editor:
%Vallendoria
In a comment:
[](https://www.worldofgaia.org/user/Vallendoria) [Vallendoria](https://www.worldofgaia.org/user/Vallendoria)